1. Field of the Invention
The present invention relates to a technology of a multi-axis temporary tightening tool which is a rotating tool for simultaneously tightening a plurality of screw members.
2. Description of Related Art
In cases such as of fastening a tire wheel to a hub with a plurality of nuts, a workpiece to attach may be fixed with a plurality of screw members (bolts, nuts, or the like) to a portion to which the workpiece is attached. For example, in an operation where the wheel is fixed to the hub with the nuts, when the nuts are tightened, generally, an operating personnel first manually tightens the nuts one by one for several threads on stud bolts implanted in the hub. The personnel then fully tightens the nuts at a prescribed torque using a tool such as a torque wrench. Hereinafter in this description, screwing a screw member such as nut or bolt for several threads to a member such as stud bolt or nut to which the screw member is screwed before fully tightening will be referred to as “temporary tightening”.
However, temporary tightening of the screw members which is manually made one by one by the operating personnel takes time and is troublesome. Therefore, for an efficient temporary tightening operation, a tool (so-called a multi-axis temporary tightening tool) has been developed which is capable of simultaneous temporary tightening of a plurality of screw members. For example, Japanese Patent Application Publication No. 2006-205274 (JP 2006-205274 A) which will be described below discloses such a technology, which has been known. “Multi-axis temporary tightening tool” described herein is a tool suitable for the use in simultaneous “temporary tightening” of a plurality of screw members (bolts, nuts, or the like). Its use is not limited to the temporary tightening of a plurality of screw members. For example, when torque controlling is not very necessary, the tool can be used for simultaneously fully tightening a plurality of screw members or can be used for simultaneously loosening a plurality of screw members that have been already tightened or for other purposes.
The multi-axis temporary tightening tool according to the conventional technology disclosed in JP 2006-205274 A has a driving gear which is rotated by a driving means, a plurality of driven gears, a toothed belt which is wound around the driving gear and the plurality of driven gears and transmits rotation of the driving gear to the plurality of driven gears, and a plurality of sockets which are coupled to the plurality of driven gears and are engaged with bolts or nuts. The driving gear is placed in a central portion of a main body of the multi-axis temporary tightening tool. The pluralities of driven gears and sockets are placed around the driving gear in the main body. In such a configuration, rotational force is input to the driving gear, and the plurality of sockets can be thereby simultaneously rotated, thus enabling simultaneous temporary tightening of the plurality of bolts and nuts.
The multi-axis temporary tightening tool according to the conventional technology disclosed in JP 2006-205274 A has a problem such that for example, in the case that the stud bolts on which the screw members are screwed are placed to surround a protruding portion, the main body of the multi-axis temporary tightening tool may interfere with the protruding portion, and thus the multi-axis temporary tightening tool cannot be used depending on the arrangement of the stud bolts. Even in such a case, the sockets are made longer than the height of the protruding portion, thereby allowing prevention of the interference between the main body of the tool and the protruding portion. However, the longer sockets result in problems such as size increase of the multi-axis temporary tightening tool and difficulty in handling of the tool.